1. Field of the Invention
This invention relates to deep fat cooking vessels generally, and more particularly to an apparatus and method for optical sensing of liquid level in such cooking vessels.
2. Description of Related Art
Large capacity, pressurized, deep fat fryer cookers (referred to as deep fat flyers, cooking devices, cookers, and the like) have been devised for cooking products in a heated and/or pressurized environment. Typically, such devices may include a cooking vessel, often referred to as a frypot, which may be filled with a cooking substance, e.g., oil, shortening, water, or the like, and heating devices surrounding or immersed in the vessel, or both, for heating the cooking substance. Products to be cooked are placed in the cooking vessel, either directly or in a container, such as a wire basket, and are cooked for a desired length of time.
The level of the cooking substance is an important factor in the overall efficiency of the cooking vessel. If the level of the cooking substance in the cooking vessel is too low, or if the cooking vessel is empty, the fryer may overheat, resulting in a risk of fire or equipment damage. In particular, the fryer may be damaged by such "dry firing."
If the level of the cooking substance is too high, placing a food product in the cooking vessel may cause the cooking substance to overflow or boil over and out of the cooking vessel. This too may result in fire or equipment damage. Moreover, such cooking substance boil-over or overflow may result in increased facility maintenance costs and increased cooking substance loss. This may further cause a reduction in operating efficiency. Thus, a desired cooking vessel cooking substance level incorporates both considerations; namely, providing a liquid level that is high enough to prevent "dry firing" and to cook food efficiently, while low enough to prevent boil-overs and excess cooking substance use.
In order to maintain the fryer operating efficiently, the cooking substance may periodically be drained from the cooking vessel to a drain pan. Unless an operator is attentive, the drain pan may already be filled with a cooking substance or other material, and a cooking substance spill may result, causing unsanitary working conditions and decreased productivity.